resetting PCM
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 875
Likes: 0
From: Los Angeles CA
resetting PCM
does anyone reset their PCM so the fuel maps and everything can go back to default/relearn?
back when i had a chrysler 300 we did this all the time and really improved throttle response and what not
i did a search but came up with nothing, but google took me here >> http://www.digitalcorvettes.com/foru...ad.php?t=45543
back when i had a chrysler 300 we did this all the time and really improved throttle response and what not
i did a search but came up with nothing, but google took me here >> http://www.digitalcorvettes.com/foru...ad.php?t=45543
Race Director
Joined: Aug 2003
Posts: 13,421
Likes: 8
From: Lake Mary Florida
Nope. Don't really notice much difference in the C5 through the last 2 years (2x4 seasons) but did so on my '93 with the LT1. Maybe the technology and programs are more sophisticated now and its not necessary any more?
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
You are correct in that they don't change. The only way to really get back to stock is to have the dealer use a TechII and put in the latest and greatest software... back to stock as such. The latest updates are available to be seen on
http://tis2web.service.gm.com/tis2web
http://tis2web.service.gm.com/tis2web
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Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
I "think" he was thinking something else. Some cars try to ADAPT to the driving style of the driver and over time change things like shift point and the like. Resetting the ECM will lose these changes. Even in those cases, I don;t think the fuel map is ever really messeed with.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 875
Likes: 0
From: Los Angeles CA
I "think" he was thinking something else. Some cars try to ADAPT to the driving style of the driver and over time change things like shift point and the like. Resetting the ECM will lose these changes. Even in those cases, I don;t think the fuel map is ever really messeed with.
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
In addition to idle learning, Long Term Fuel Trims definitely do change over time, and will reset to zero after a battery disconnect or PCM reflash.
LTFTs usually stick around zero on a stock engine, so no difference doing this on an all stock car...but once things like air filter and headers (or more) go on, trims start to go positive and richening up the car to compensate for the additional airflow it's moving. (this is a big part of what a tune corrects - getting those corrective trims back to around 0 is the goal).
When people in that situation (positive trims) disconnect the battery, they usually do notice a difference right after the reset. Throttle response may be better, idle smoothness may be better, and WOT will feel stronger...but it's all because car is running leaner than it was.
Over time, the trims will go back to being positive, and the car will gradually start to feel sluggish again.
If anyone finds their car acts this way after a reset, it's a pretty good indicator that a tune would be beneficial.
LTFTs usually stick around zero on a stock engine, so no difference doing this on an all stock car...but once things like air filter and headers (or more) go on, trims start to go positive and richening up the car to compensate for the additional airflow it's moving. (this is a big part of what a tune corrects - getting those corrective trims back to around 0 is the goal).
When people in that situation (positive trims) disconnect the battery, they usually do notice a difference right after the reset. Throttle response may be better, idle smoothness may be better, and WOT will feel stronger...but it's all because car is running leaner than it was.
Over time, the trims will go back to being positive, and the car will gradually start to feel sluggish again.
If anyone finds their car acts this way after a reset, it's a pretty good indicator that a tune would be beneficial.
